From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760763AbaJaOkX (ORCPT ); Fri, 31 Oct 2014 10:40:23 -0400 Received: from mailout3.w1.samsung.com ([210.118.77.13]:59331 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759301AbaJaOkU (ORCPT ); Fri, 31 Oct 2014 10:40:20 -0400 MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 X-AuditID: cbfec7f4-b7f6c6d00000120b-c9-54539f514db6 Content-transfer-encoding: 8BIT Message-id: <1414766416.6537.6.camel@AMDC1943> Subject: Re: [PATCH v8 1/5] PM / Runtime: Add getter for querying the IRQ safe option From: Krzysztof Kozlowski To: Pavel Machek Cc: "Rafael J. Wysocki" , Len Brown , Jonathan Corbet , Russell King , Dan Williams , Vinod Koul , Ulf Hansson , Alan Stern , linux-pm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Lars-Peter Clausen , Michal Simek , Kyungmin Park , Marek Szyprowski , Bartlomiej Zolnierkiewicz Date: Fri, 31 Oct 2014 15:40:16 +0100 In-reply-to: <20141031142241.GA17547@amd> References: <1413795888-18559-1-git-send-email-k.kozlowski@samsung.com> <1413795888-18559-2-git-send-email-k.kozlowski@samsung.com> <1414746895.6797.3.camel@AMDC1943> <20141031142241.GA17547@amd> X-Mailer: Evolution 3.10.4-0ubuntu2 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupjkeLIzCtJLcpLzFFi42I5/e/4Vd3A+cEhBuu7TC02zljPavHkQDuj xfSpFxgtVk/9y2pxtukNu8WSyfNZLWZN2ctksbBtCYvF5V1z2Cw+9x5htLh9mddi7ZG77Bbv XkZY3D11lM3izOlLrBYTfl9gszi+NtziZd9+Fgchj5bmHjaPxXteMnncubYHyOqbzOqx5M0h Vo8tV9tZPGbf/cHo0bdlFaPHitXf2T0+b5Lz2Pv5N0sAdxSXTUpqTmZZapG+XQJXxoRZ01kK dghUzN6xkbmB8QdPFyMHh4SAicSvX9ZdjJxAppjEhXvr2boYuTiEBJYySpxfs4sNJMErICjx Y/I9FpB6ZgF5iSOXskHCzALqEpPmLWKGqP/MKPFiywVWiHo9idUrprCD2MIC4RL3l20Bi7MJ GEtsXr4EbKYI0JytfSvAmpkFulklOmbPBkuwCKhK7LvSygRicwpoSvxp3cMIseE4o8S21sVM EFcrSzT2u01gFJiF5L5ZCPfNQnLfAkbmVYyiqaXJBcVJ6bmGesWJucWleel6yfm5mxghcfhl B+PiY1aHGAU4GJV4eFdIBocIsSaWFVfmHmKU4GBWEuH90QEU4k1JrKxKLcqPLyrNSS0+xMjE wSnVwChbFTR1/70C1VCfyBOP5HyN2oqyNjHOUgmtkSxtmhkeXGLtMX/ip4htrXKOm2f28rJf mDRl9dlJChxvtKxPVcQxTny/6Vw8j8O0mC8xKsFX9gsUHdow6y9nEu+vuYopT+auSHa/xpq6 uP5N4t30fR0XMu6d4H31wcuG7dnfDMZ/q89sWuofFafEUpyRaKjFXFScCABIFBvdoQIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On pią, 2014-10-31 at 15:22 +0100, Pavel Machek wrote: > On Fri 2014-10-31 10:14:55, Krzysztof Kozlowski wrote: > > On pon, 2014-10-20 at 11:04 +0200, Krzysztof Kozlowski wrote: > > > Add a simple getter pm_runtime_is_irq_safe() for querying whether runtime > > > PM IRQ safe was set or not. > > > > > > Various bus drivers implementing runtime PM may use choose to suspend > > > differently based on IRQ safeness status of child driver (e.g. do not > > > unprepare the clock if IRQ safe is not set). > > > > > > Signed-off-by: Krzysztof Kozlowski > > > Reviewed-by: Ulf Hansson > > > > Rafael, Len, Pavel, > > > > Is proposed API ok? Do you have any comments? > > > > I'll upload whole patchset to Russell's patch tracking system. However > > an ack from PM maintainer is probably needed. > > I don't like the API. Having callbacks work in different context (irq > / noirq) based on what another function reports is ugly. > > What is the penalty if we always decide callbacks are not IRQ safe? Then pm_runtime_get_sync() could not be called in atomic context. The pl330 runtime PM would have to be completely reworked because one pm_runtime_get_sync() is called in device_issue_pending which cannot sleep (at least in non preemptible kernels). Probably this can be solved some way... Best regards, Krzysztof > > > > --- a/Documentation/power/runtime_pm.txt > > > +++ b/Documentation/power/runtime_pm.txt > > > @@ -468,6 +468,10 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: > > > - set the power.irq_safe flag for the device, causing the runtime-PM > > > callbacks to be invoked with interrupts off > > > > > > + bool pm_runtime_is_irq_safe(struct device *dev); > > > + - return true if power.irq_safe flag was set for the device, causing > > > + the runtime-PM callbacks to be invoked with interrupts off > > > + > > > void pm_runtime_mark_last_busy(struct device *dev); > > > - set the power.last_busy field to the current time > > >